权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

The influence of Yellow-sand (KOSA) on the forest, the presumption of the sulfur sources identification and the contribution rate of dry deposition

黄沙(KOSA)对森林的影响、硫源识别推论及干沉降贡献率

基本信息

批准号：
15380114
负责人：
SAKAI Masaharu
金额：
$ 7.23万
依托单位：
Forestry and Forest Products Research Institute
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

In this research, it aims to evaluate the influence of Yellow-sand (KOSA) on the forest, to identify sulfur sources of SO_4^<2-> of rainwater (precipitation, thoughfall, stemflow) by the sulfur isotopic method, and to estimate contribution rate of dry deposition on total deposition.The outline of the result at all periods is as follows.We investigated qualitative change of rainwater in an evergreen broadleaved forest in a southern part of Japan1. KOSA flies from a continental desert to Japan at the early spring. Observation frequency of KOSA is an increasing tendency for the long term. In the spring of 2002 when the especially maximum KOSA in Beijing was observed, the color of aerosol filter presented yellowish. The Ca^<2+> concentration of the aerosol at KOSA event became 20-70nmol/m^3, and was higher than these values (20 nmol/m^3 or less) at normal event. The ion concentrations in precipitation, thoughfall and stemflow at KOSA event were higher than these at normal event. The influe … More nce on the forest by KOSA was admitted.2. The sulfate concentration and sulfur isotopic ratio of the wet deposition at 20 precipitation events and the dry deposition at 9 precipitation events were determined. The SO_4^<2-> concentrations increased in the order of precipitation, throughfall and stemflow, whereas their sulfur isotopic ratio( δ^<34>S) decreased in the order of precipitation, throughfall and stemflow. These results suggest that δ^<34>S-depleted light sulfur is added to throughfall and stemflow. On the other hand, δ^<34>S values of aerosol and gas were +2.7〜+5.3‰ and-2.1〜2.0‰, respectively. The latter is light enough to reduce the δ^<34>S values of throughfall and stemflow. Therefore we concluded that 1) SO_2 in dry deposition is the main substance causing low pH of stemflow and throughfall, 2) a lot of SO_4^<2-> with light δ^<34>S value are loaded to precipitation flowing down as stemflow and throughfall.3. About 60 percent of total deposition (wet deposition and dry deposition) was loaded to the forest by a dry deposition, using the mass balance model. Less

本研究的目的是评价黄沙对森林的影响，<2->用硫同位素方法确定雨水（降水、降雨、树干径流）中SO_4 ~（2+）的硫源，估算干沉降对总沉降的贡献率。KOSA在早春从大陆沙漠飞往日本。KOSA的观察频率长期呈上升趋势。2002年春季北京观测到KOSA极大值时，气溶胶滤片颜色呈淡黄色。KOSA事件时气溶胶中Ca^2+浓度为20- 70 nmol/m^3，高于正常事件时的Ca ^2+浓度（20 nmol/m^3或更低）。KOSA事件的降水、降雨和树干茎流中离子浓度均高于正常事件。影响力 ...更多信息在森林中的一次由KOSA被承认。测定了20次降水过程湿沉降和9次降水过程干沉降的硫酸盐浓度和硫同位素比值。SO_4 ~（2-<2->）浓度按降水、穿透雨、树干径流的顺序增加，而硫同位素比值（δ^<34>S）按降水、穿透雨、树干径流的顺序减小。这些结果表明，δ^<34>S贫化的轻硫被添加到穿透雨和茎流中。气<34>溶胶和气体的δ^ S值分别为+2.7 ‰ +5.3‰和-2.1 ‰-2.0 ‰。后者的光照足以降低<34>穿透雨和树干茎流的δ^ S值。因此我们得出结论：1）干沉积物中的SO_2是导致茎流和穿透雨pH值低的主要物质; 2）<2->大量δ^<34>S值较低的SO_4^作为茎流和穿透雨负载到流下的降水中。3.利用质量平衡模型，干沉降量约占总沉降量（湿沉降和干沉降）的60%。少